1. Field of the Invention
The present invention relates to an apparatus and method for detecting radar signals, and more particularly to an apparatus and method for collaboratively detecting radar signals.
2. Description of the Related Art
Because the bandwidth adopted by IEEE 802.11 overlaps that used by some radar devices, IEEE 802.11h recommends a Dynamic Frequency Selection (DFS) technique to avoid such frequency conflict. With the DFS technique, when frequency conflicts are detected, the utilized frequency will hop to a conflict-free channel and continue detecting radar signals in order to prevent interference problems.
However, the DFS technique does not provide an available solution of detecting radar signals. IEEE 802.11h recommends stopping signal transmission when radar signals are detected so as to reduce interference signals. However, the above method would largely reduce the throughput of the system and thus has not been embraced by the industry.
M. Wen, L. Hanwen, “Radar detection for 802.11a systems in 5 GHz band,” International Conference on Wireless Communications, Networking and Mobile Computing, 2005, pp. 512-514 discloses a radar-detecting algorithm that detects radar signals based on power increasing or decreasing of adjacent sampling signals. However, this method fails when the radio local area network (RLAN) and radar signals are at the same power magnitude.
U.S. Pat. No. 6,697,013 discloses another radar-detecting algorithm that detects radar signals based on correlation among signals, pulse width and zero crossing. However, it amounts to a lot of hardware cost due to conducting comparisons between the real and imaginary parts of the frequency domain and time domain of signals.